The present invention generally relates to a method and an apparatus for a continuous basis neutralization of oxidation product components found in rerefined used oil supplies. More particularly, the invention relates to a latter-stage treatment of used oil stock that had been previously subjected to rerefining treatments but which still contains oxidation products that are susceptible to treatment with a strong base or the like.
The rerefining of used lubricating oil stock typically includes a plurality of treatment procedures that are intended to result in the removal of undesirable components or to otherwise modify the used oil stock so that same generally equals or closely approximates the properties and appearance of virgin oil stock. Examples of systems in this regard include those disclosed in Kim et al U.S. Pat. No. 4,101,414. Systems such as these will usually include clarifying steps, typically near the end of the overall rerefining scheme, which are carried out in order to address difficult removal problems for specific components which are not removed during earlier stages of these rerefining processes. Examples of such latter-stage treatment procedures include those carried out in the clay contact still of said U.S. Pat. No. 4,101,414. Other examples of such latter-stage treatments include removal of halogenated polyphenyl materials from rerefined used oil stocks, an example of which is disclosed in O'Connell et al U.S. Pat. No. 4,623,448.
Latter-stage treatments which include distilling rerefined stock in the presence of clay typically also involve filtering the clay distilled stock and collecting the filtered stock as a rerefined oil product. This procedure requires the input of substantial quantities of acid activated clays and/or neutral clays and results in the formation of large amounts of filter cake of spent clay and residual oil. The input of these substantial quantities of clays represents a substantial expense, and the formation of such large quantities of filter cake presents an extremely difficult disposal problem.
These types of clay-contact distillation procedures that are utilized as a latter-stage treatment are intended to clean, clarify, deodorize and lower the acid value of the oil stock. These are beneficial results, but the disadvantages attendant to using such large volumes of clays are great and present an increasingly undesirable disposal problem which faces an industry that is otherwise highly favored because of its important contribution to the conservation of petroleum resources.
It has been known to utilize strong bases in the treatment of used petroleum and lubricant products. Often such treatments are other than latter-stage treatments which are carried out on stocks that have already been subjected to rerefining procedures. Also, such uses of strong bases and the like have heretofore typically been carried out in a batch type of procedure which tends to be overly time-consuming and generally inefficient.
By the present invention, used oil stocks that are being subjected to rerefining procedures include subjecting same to a latter-stage process that neutralizes oxidation product components on a continuous-flow basis. This continuous procedure includes providing and flowing a supply of rerefined used oil stock that is contaminated with oxidation product components. A supply of strong base is introduced into the supply of flowing stock. This stock is introduced into a distillation chamber and is vaporized and flows on a continuous basis into an array of impingement surfaces onto which the thus treated vaporized stock condenses for collection and outflow from the distillation chamber on a substantially continuous basis. The procedure of this invention is extremely cost efficient and very effective in neutralizing oxidation product components in a manner that does not generate large quantities of treatment byproduct which create a disposal or treatment problem.
It is accordingly a general object of this invention to provide an improved procedure for treating rerefined used oil stock with a basic treatment agent on a continuous basis.
Another object of the present invention is to provide an improved method and apparatus for continuously removing oxidation product components from rerefined used oil supplies without having to resort to the use of treatment agents that are difficult to dispose of, such as clay compositions.
Another object of the present invention is to provide an improved method and apparatus for rerefining used lubricating oil stocks, transformer oils and the like, including removal of oxidation product contaminants, particularly those that are acidic.
Another object of this invention is to provide an improved method and apparatus for effecting a latter-stage rerefining treatment of used oil stocks which results in color clarification, odor reduction and acid number reduction to substantially zero.
Another object of this invention is to provide an improved rerefining method and apparatus which substantially eliminates the production of a rerefined stock having a high chlorine content which would otherwise be a source of difficulties for subsequent latter-stage treatment steps, such as those utilizing a hydrotreater.
Another object of this invention is to provide a rerefining method and apparatus that will effectively treat waste oil stocks having relatively high chlorine contents.
Another object of the present invention is to provide an improved rerefining apparatus and method which utilizes extremely low concentrations of caustic or other bases while effectively and efficiently clarifying and neutralizing acid values of waste oil stock.
These and other objects, features and advantages of this invention will be clearly understood through a consideration of the following detailed description.